means—
| (a) | being under the influence of intoxicating liquor or a drug having a narcotic effect; |
| (b) | a contravention of any law for the protection or the health of employees or for the prevention of accidents, if such contravention was committed wilfully or with a reckless disregard of the provisions of such law; or |
| (c) | any other act or omission which the Director-General having regard to all the circumstances considers to be serious and wilful misconduct; |